1. Field of the Invention
The present invention relates to a hydraulic valve lash adjuster of a direct-drive type, and more specifically, to a hydraulic valve lash adjuster with which a cam engages directly and in which an oil-introducing chamber can be easily cleaned by washing.
2. Description of Related Art
A conventional hydraulic valve lash adjuster of the direct-drive type includes a hollow cylindrical body with which a cam engages directly, and is slidably mounted within a bore formed in a cylinder head. The body is provided with a cylinder sleeve which is located coaxially with the body. There is formed an annular oil-introducing chamber between the inner surface of the body and the outer surface of the cylinder sleeve. The cylinder sleeve is provided therein with a hydraulic unit.
Engine-operating oil is introduced through the oil-introducing chamber into the hydraulic unit. The oil-introducing chamber is closed up except for one inlet and outlet so as to store sufficient oil therein. Thus, the valve lash adjuster is constructed so that no substantial quantity of air will come into the hydraulic unit even when the engine is started and no oil is being supplied to the valve lash adjuster.
Accordingly, in the conventional hydraulic valve lash adjuster of the direct-drive type in which the oil-introducing chamber is closed up except for one inlet and outlet it is difficult to remove from the oil-introducing chamber any extraneous substance such as chips or particles which accidentally enter it. In particular, during the manufacturing process of the body, cleaning of the interior of the body or the oil-introducing chamber by washing is very difficult. Therefore, if such chips and particles generated during the manufacturing process remain unremoved within the body, they will find their way into the hydraulic unit during the operation of the engine and prevent smooth sliding operation of the hydraulic unit. Consequently, the hydraulic valve lash adjuster as a whole will no longer be able to fulfill its function.